WORK MACHINE

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is a 35 U.S.C. § 371 national stage application of PCT International Application No. PCT/KR2022/015854 filed on Oct. 18, 2022, the disclosure and content of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to a working machine, and more particularly, to a working machine equipped with a quick coupler.

BACKGROUND

Working machines that perform work by obtaining power from the pressure of high-pressure fluid are known. Some of these working machines are equipped with quick couplers for easy attachment and detachment of working tools that perform the work.

FIG. 1 is a drawing schematically showing a conventional quick coupler.

As shown, the quick coupler 100 may be equipped with a quick coupler cylinder 130. When fluid is supplied to the bottom chamber of the quick coupler cylinder 130 through the port 134a, the first wedge 128 moves to the right based on the drawing and the second wedge 129 moves to the left based on the drawing so that the quick coupler 100 is coupled with the working tool (the fastening pin 125 of the working tool) (coupling position). Conversely, when fluid is supplied to the rod side chamber of the quick coupler cylinder 130 through the port 134b, the first wedge 128 moves to the left based on the drawing and the second wedge 129 moves to the right based on the drawing so that the quick coupler 100 is uncoupled with the working tool (the fastening pin 125 of the working tool) (uncoupling position).

In addition, the quick coupler 100 may be equipped with an elastic member 142 that applies elastic force to couple the quick coupler 100 and the working tool (the fastening pin 125 of the working tool). The elastic member 142 is located within the cylinder of the quick coupler 100 and applies elastic force to the rod 135 and the wedge fixture 137.

The drawing symbol 121 represents the body of the quick coupler 100, 124 represents a hook, 139 represents a support block, 140 represents a guide, and 141 represents a pin.

SUMMARY

A working machine according to a first aspect of the present disclosure comprises: a tank; a working fluid pump configured to receive a fluid from the tank and pressurize it to discharge a working fluid; a quick coupler configured to have a coupling position to be coupled to a working tool, and an uncoupling position to be uncoupled from the working tool by the pressure of a first working fluid received the working fluid pump; a flow control valve positioned between the working fluid pump and the tank, and switched between a neutral position for allowing a flow of a second working fluid returned from the working fluid pump to the tank and a non-neutral position for blocking a flow of the second working fluid returned from the working fluid pump to the tank, and configured to control a flow rate of a flow of the second working fluid returned from the working fluid pump to the tank according to a switching amount from the neutral position to the non-neutral position; an input unit for receiving an uncoupling command between the working tool and the quick coupler; and a control unit for controlling the flow control valve, wherein the flow control valve is switched to the non-neutral position while the uncoupling command input to the input unit is maintained, and then the switching amount of the flow control valve from the neutral position to the non-neutral position is reduced but greater than zero.

According to the first aspect of the present disclosure, there is an advantage in that problems of shock occurring due to the hydraulic pressure used to uncouple the quick coupler when operating the working device and making fine manipulation difficult, making it difficult to locate the quick coupler in the correct position corresponding to the working tool, can be solved.

According to one example of the present disclosure, the control unit controls the flow control valve such that, while the uncoupling command input to the input unit is maintained, when a preset time has elapsed after the uncoupling command is input to the input unit, the switching amount of the flow control valve from the neutral position to the non-neutral position is reduced from a first switching amount to a second switching amount, wherein the first switching amount may be greater than the second switching amount.

According to one example of the present disclosure, the preset time may be equal to or greater than the time required for the quick coupler to switch to the uncoupling position.

According to one example of the present disclosure, the second switching amount may be equal to or greater than a minimum switching amount required to keep the quick coupler in the uncoupling position.

According to one example of the present disclosure, the quick coupler comprises an elastic member that applies a force to couple the quick coupler and the working tool, and when the flow control valve is switched to the second switching amount, a force due to the pressure of the first working fluid may be at least greater than the force due to the elastic member.

According to one example of the present disclosure, when the flow control valve is switched to the first switching amount, the outlet pressure of the working fluid pump may be greater than the outlet pressure of the working fluid pump when the flow control valve is switched to the second switching amount.

According to one example of the present disclosure, it further comprises a driving unit that drives the working fluid pump, and the control unit, according to a preset relationship in which the second switching amount decreases as the rotational speed of the driving unit increases, can control the flow control valve so that the size of the second switching amount varies depending on the size of the rotational speed of the driving unit.

According to one example of the present disclosure, the control unit may comprise, while the uncoupling command input to the input unit is maintained, a signal generating unit that operates the flow control valve by generating a signal to decrease the switching amount of the flow control valve from the neutral position to the non-neutral position to be greater than zero.

According to one example of the present disclosure, a pilot pump may be additionally included, wherein the signal is a hydraulic signal, and the signal generating unit may include an electronic proportional pressure reducing valve located between the pilot pump and the flow control valve, and switched between a first position that blocks the flow of the pilot fluid from the pilot pump to the flow control valve and a second position that allows the flow of the pilot fluid from the pilot pump to the flow control valve, and generating the hydraulic signal by controlling the pressure of the pilot fluid flowing to the flow control valve according to the switching amount from the first position to the second position.

According to one example of the present disclosure, the switching amount from the first position to the second position is determined by an electric signal applied to the electronic proportional pressure reducing valve, and while the uncoupling command input to the input unit is maintained, the current value of the electric signal may be configured to be greater than zero but decrease.

According to one example of the present disclosure, while the uncoupling command input to the input unit is maintained, when a preset time has elapsed after the uncoupling command is input to the input unit, the current value of the electric signal is configured to decrease from a first current value to a second current value, wherein the first current value may be greater than the second current value.

According to one example of the present disclosure, the second current value may be equal to or greater than a minimum current value required to keep the quick coupler in the uncoupling position.

According to one example of the present disclosure, the quick coupler includes an elastic member that applies a force to couple the quick coupler and the working tool, and it may be permissible to set the size of the second current value according to the size of the force by the elastic member.

According to one example of the present disclosure, the driving unit for driving the working fluid pump may be additionally included, and the control unit, according to a preset relationship in which the second current value decreases as the rotational speed of the driving unit increases, may additionally include an electronic control unit for controlling the electronic proportional pressure reducing valve so that the size of the second current value varies depending on the size of the rotational speed of the driving unit.

According to one example of the present disclosure, the signal generating unit may additionally include a signal applying valve located between the electronic proportional pressure reducing valve and the flow control valve to allow or block the hydraulic signal from being applied to the flow control valve.

According to one example of the present disclosure, when the uncoupling request is input to the input unit, the signal applying valve may allow the hydraulic signal to be applied to the flow control valve.

According to one example of the present disclosure, it may further comprise a quick coupling valve located between the working fluid pump and the quick coupler, and having a first position and a second position allowing a flow of the first working fluid from the working fluid pump to the quick coupler, thereby uncoupling the quick coupler from the working tool.

According to one example of the present disclosure, when the uncoupling command is input to the input unit, the quick coupling valve allows the flow of the first working fluid from the working fluid pump to the quick coupler, so that the working tool can be uncoupled from the quick coupler.

According to one example of the present disclosure, the quick coupler includes a quick coupler cylinder, and when the uncoupling command is input to the input unit, the quick coupling valve allows the flow of the first working fluid from the working fluid pump to the quick coupler cylinder and can operate the quick coupler cylinder so that the working tool is uncoupled from the quick coupler.

It additionally includes a flow path connecting the working fluid pump and the flow control valve, a swing actuator control valve connected to the flow path, and a swing actuator, wherein the swing actuator control valve is connected to the swing actuator and can control the flow rate supplied from the working fluid pump to the swing actuator.

The above aspects, the appended claims and the examples disclosed herein either above or below may be appropriately combined with each other, as will be apparent to a person skilled in the art.

Additional features and advantages are disclosed in the following description, claims and drawings, and additional features and advantages will to some extent be readily apparent to a person skilled in the art or may be understood by practicing the disclosure described herein. Additionally, control units, computer-readable media and computer program products related to the aforementioned technical advantages are disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure, cited as examples, are described in detail below with reference to the attached drawings.

FIG. 1 is a drawing schematically showing an example of a conventional quick coupler.

FIG. 2 is a drawing schematically showing a working machine according to an example of the present disclosure.

FIG. 3 is a graph showing the switching amount of a flow control valve and the outlet pressure of a working fluid pump in a working machine according to a comparative example.

FIG. 4 is a graph showing the switching amount of a flow control valve and the outlet pressure of a working fluid pump in a working machine according to an example of the present disclosure.

FIG. 5 is a drawing schematically showing a working machine according to an example of the present disclosure.

FIG. 6 is a drawing schematically showing a working machine according to an example of the present disclosure.

FIG. 7 is a graph showing the current value applied to an electronic proportional pressure reducing valve, the switching amount of a flow control valve, and the outlet pressure of a working fluid pump in a working machine according to an example of the present disclosure.

FIG. 8 is a drawing schematically showing a working machine according to an example of the present disclosure.

FIG. 9 is a drawing schematically showing a working machine according to an example of the present disclosure.

FIG. 10 is a graph showing the results of adjusting the current value input to an electronic proportional pressure reducing valve according to the rotational speed setting of a driving unit.

DETAILED DESCRIPTION

Aspects of the present disclosure, cited as examples, are described in detail below with reference to the attached drawings. The aspects described below provide information necessary to enable a person of ordinary skill in the art to practice the present disclosure.

FIG. 2 is a drawing schematically showing a working machine according to an example of the present disclosure.

The working machines of the present disclosure may include various machines that perform work by obtaining power from hydraulics, such as heavy equipment, particularly construction equipment such as an excavators, but the present disclosure is not limited thereto.

The working machine may include a tank 200, a working fluid pump 330, a quick coupler 100, a flow control valve 430, an input unit 700, and a control unit 500.

The working fluid pump 330 may receive fluid from the tank 200, pressurize it, and discharge the working fluid.

The quick coupler 100 may be a quick coupler 100 having a known structure, and may have, for example, the structure of FIG. 1. However, the quick coupler 100 of FIG. 1 is merely for illustrative purpose and may have numerous different structures. It should be noted that the structure of FIG. 1 is merely a simple example rather than a typical or representative example of a quick coupler 100 of the working machine of the present disclosure. Since the quick coupler 100 of a known structure exists in many different structures, a detailed description of each of them will be omitted. However, those of ordinary skill in the art will be able to easily incorporate the quick couplers 100 of various structures into the working machine of the present disclosure.

The quick coupler 100 may have a coupling position and an uncoupling position. When the quick coupler 100 is in the coupling position, the quick coupler 100 may be coupled with a working tool. The quick coupler 100 receives a first working fluid from the working fluid pump 330 and may be uncoupled from the working tool by the pressure of the first working fluid (uncoupling position).

In this specification, the term ‘working device’ is used to refer to a combination of, for example, a boom, arm and bucket of an excavator, and the term ‘working tool’ is used to refer to, for example, a bucket coupled to a quick coupler 100. Additionally, ‘working tool’ may also be used to refer to devices such as breakers, shears, augers, drills, and the like. Typically, the quick coupler 100 is fixed to the end of the arm, and a bucket is coupled to the quick coupler 100. However, the present disclosure is not limited thereto.

In some examples, the quick coupler 100 may include a quick coupler 100 cylinder, as shown in FIG. 1. FIG. 1 illustrates an example in which fluid is supplied to the bottom chamber of the quick coupler cylinder for coupling and fluid is supplied to the rod side chamber of the quick coupler cylinder for uncoupling, but it should be noted that this is merely an example and the present disclosure is not limited to this example.

In some examples, the quick coupler 100 may include an elastic member, such as a spring, that applies a force to couple the quick coupler 100 and the working tool, as shown in FIG. 1. Although FIG. 1 illustrates an example in which an elastic member is located in the quick coupler 100 cylinder to apply elastic force to a piston (a rod 135 and a wedge fixture 137 in FIG. 1), the present disclosure is not limited thereto, and in numerous different quick coupler 100 structures, the elastic member may be installed on the outside of the quick coupler 100 cylinder to apply elastic force to components other than the piston. As described above, the quick coupler 100 structure of FIG. 1 is merely a simple example, and it should be noted that the present disclosure is not limited to this example.

The flow control valve 430 is located between the working fluid pump 330 and the tank 200. The flow control valve 430 may be switched between a neutral position and a non-neutral position. When the flow control valve 430 is in the neutral position (as shown in FIG. 2), the flow control valve 430 may allow the flow of a second working fluid discharged from the working fluid pump 330 and returned to the tank 200. When the flow control valve 430 is in the non-neutral position, the flow control valve 430 may block the flow of a second working fluid discharged from the working fluid pump 330 and returned to the tank 200. The flow control valve 430 may control the flow rate of flow of the second working fluid returned from the working fluid pump 330 to the tank 200 according to the switching amount from the neutral position to the non-neutral position.

The input unit 700 receives an uncoupling command for the working tool and the quick coupler 100. Typically, the input unit 700 may be an operator input unit that receives an uncoupling command from a driver, but the present disclosure is not limited thereto. For example, it is also possible to receive an uncoupling command from another device. Additionally, the uncoupling command may be a direct command, such as switch-on, but it may also be an indirect command that is interpreted as an uncoupling command and results in uncoupling of the working tool and the quick coupler. The working machine may uncouple the quick coupler 100 by supplying the working fluid to the quick coupler 100, for example, with simple switch-on of the input unit 700, without operating, for example, the RCV lever (not shown) to generate pressure for uncoupling.

The control unit 500 controls the flow control valve so that, while the uncoupling command input to the input unit 700 is maintained, the flow control valve 430 is switched to a non-neutral position, and then the switching amount of the flow control valve from the neutral position to the non-neutral position is greater than zero but decreases. That is, the control unit 500 is an execution unit that executes the uncoupling command input to the input unit 700.

FIG. 3 is a graph showing the switching amount of a flow control valve and the outlet pressure of a working fluid pump in a working machine according to a comparative example.

When an uncoupling command (UC) is input to the input unit 700, the switching amount of the flow control valve 430 from the neutral position to the non-neutral position may be configured to be greater than zero while the uncoupling command input to the input unit 700 is maintained. If the switching amount from the neutral position to the non-neutral position is greater than zero, that is, if the flow control valve 430 switches from the neutral position to the non-neutral position, the flow rate returned to the tank 200 decreases as the switching amount increases, and as a result, the pressure of the fluid in the flow path 910 between the working fluid pump 330 and the flow control valve 430 and the pressure of the fluid in the flow path 920 between the working fluid pump 330 and the quick coupler 100 increase. By utilizing the increased pressure of the fluid in the flow path 920 between the working fluid pump 330 and the quick coupler 100, the quick coupler 100 may be operated from the coupling position to the uncoupling position.

Meanwhile, for example, when uncoupling a quick coupler 100 with a certain working tool and then coupling it with another working tool, it may be necessary to swing the upper structure from the position where the uncoupled working tool is placed to the position where another working tool to be coupled is placed. To this end, the swing actuator control valve 410 (see FIG. 9) is switched to supply the working fluid from the working fluid pump 330 to the swing actuator 411 (see FIG. 9), but if the swing actuator control valve is switched while the pressure of the fluid in the flow path between the working fluid pump 330 and the flow control valve 430 is increased, the increased hydraulic pressure is suddenly supplied to the swing actuator, causing a shock and making it difficult to perform a fine swing operation, making it difficult to swing the upper body to the exact position where another working tool to be coupled is placed.

Therefore, according to the present disclosure, as illustrated in FIG. 4, when an uncoupling command (UC) is input to the input unit 700, the switching amount of the flow control valve 430 from the neutral position to the non-neutral position may be configured to decrease while the uncoupling command input to the input unit 700 is maintained.

FIG. 4 is a graph showing the switching amount of a flow control valve and the outlet pressure of a working fluid pump in a working machine according to an example of the present disclosure.

In some examples, when an uncoupling command (UC) is input to the input unit 700, while the uncoupling command input to the input unit 700 is maintained, the switching amount from the neutral position to the non-neutral position may be configured to decrease from a first switching amount S1 to a second switching amount S2 if a preset time (T1) elapses after the uncoupling command (UC) has been input to the input unit 700. Here, the first switching amount (S1)>the second switching amount (S2)>0.

In some examples, the preset time (T1) may be equal to or greater than the time it takes for the quick coupler 100 to switch to the uncoupling position. By providing a large switching amount of S1 until the quick coupler 100 is switched to the uncoupling position, the quick coupler 100 can be quickly switched to the uncoupling position, thereby enabling a quick response to, for example, a driver's uncoupling command, and once the quick coupler 100 is switched to the uncoupling position, the switching amount is reduced from S1 to S2, thereby preventing the occurrence of the shock described above.

In some examples, the second switching amount S2 may be equal to or greater than the minimum switching amount required to keep the quick coupler 100 in the uncoupling position. This is because when the second switching amount S2 becomes smaller than the minimum switching amount, the quick coupler 100 can be switched to the coupling position.

In some examples, the force due to the pressure of the first working fluid applied to the quick coupler 100 when the flow control valve 430 is switched to the second switching amount S2 may be at least greater than the force due to the elastic member that applies force to couple the quick coupler 100 and the working tool. When the flow control valve 430 is switched to the second switching amount S2, if the force due to the pressure of the first working fluid becomes smaller than the force due to the elastic member, the quick coupler 100 can be switched to the coupling position by the force due to the elastic member.

In some examples, when the flow control valve 430 is switched to the second switching amount S2, the outlet pressure P2 of the working fluid pump 330 may be smaller than the outlet pressure P1 of the working fluid pump 330 when the flow control valve 430 is switched to the first switching amount S1.

FIG. 5 is a drawing schematically showing a working machine according to an example of the present disclosure.

In some examples, the control unit 500 may include a signal generating unit 530. The signal generating unit 530 can operate the flow control valve 430 by generating a signal to decrease the switching amount of the flow control valve 430 from the neutral position to the non-neutral position to be greater than zero while the uncoupling command input to the input unit 700 is maintained.

FIG. 6 is a drawing schematically showing a working machine according to an example of the present disclosure.

In some examples, the signal generated by the signal generating unit 530 may be a hydraulic signal. To generate such a hydraulic signal, the signal generating unit 530 may include an electronic proportional pressure reducing valve 531. The electronic proportional pressure reducing valve 531 can be located between the pilot pump (see FIG. 9) and the flow control valve 430. The electronic proportional pressure reducing valve 531 can be switched between a first position that blocks the flow of pilot fluid from the pilot pump to the flow control valve 430 and a second position that allows the flow of pilot fluid from the pilot pump to the flow control valve 430. The electronic proportional pressure reducing valve 531 can generate a hydraulic signal by controlling the pressure of the pilot fluid flowing to the flow control valve 430 according to the switching amount from the first position to the second position.

FIG. 7 is a graph showing the current value applied to the electronic proportional pressure reducing valve 531, the switching amount of the flow control valve 430, and the outlet pressure of the working fluid pump in a working machine according to an example of the present disclosure.

The switching amount from the first position to the second position can be determined by an electric signal applied to the electronic proportional pressure reducing valve 531. After an uncoupling command (UC) is input to the input unit 700, the current value of the electric signal may be greater than zero while the uncoupling command (UC) input to the input unit 700 is maintained. Additionally, the current value of the electric signal may be configured to decrease while the uncoupling command (UC) input to the input unit 700 is maintained. In some examples, while the uncoupling command (UC) input to the input unit 700 is maintained, the current value of the electric signal may be configured to decrease from the first current value (I1) to the second current value (I2) when a preset time has elapsed after the uncoupling command (UC) is input to the input unit 700. Here, the first current value (I1)>the second current value (I2)>0. In some of these examples, the second current value (I2) may be equal to or greater than the minimum current value required to keep the quick coupler 100 in the uncoupling position.

FIG. 8 is a drawing schematically showing a working machine according to an example of the present disclosure.

In some examples, the working machine may include a quick coupling valve 600 located between the working fluid pump 330 and the quick coupler 100. In some examples, the quick coupling valve 600 may have a first position and a second position that allows the flow of a first working fluid from the working fluid pump 330 to the quick coupler 100 to uncouple the quick coupler 100 from the working tool.

FIG. 9 is a drawing schematically showing a working machine according to an example of the present disclosure.

In some examples, the signal generating unit 530 may include a signal applying valve 533 located between the electronic proportional pressure reducing valve 531 and the flow control valve 430 to allow or block a hydraulic signal from being applied to the flow control valve 430.

When an uncoupling request is inputted to the input unit 700, a signal according to the request is received and the signal applying valve 533 can allow a hydraulic signal from the electronic proportional pressure reducing valve 531 to be applied to the flow control valve 430. In addition, when an uncoupling request is input to the input unit 700, the quick coupling valve 600 receives a signal according to the request and allows the flow of the first working fluid from the working fluid pump 330 to the quick coupler 100, so that the working tool can be uncoupled from the quick coupler 100. To this end, the input unit 700 can be connected to the signal applying valve 533 and the quick coupling valve 600, respectively.

In some examples, the flow control valve 430 may be a straight travel valve. In some examples, it may include a swing actuator control valve 410 connected to a flow path connecting a working fluid pump 330 and a flow control valve 430. The swing actuator control valve 410 is connected to the swing actuator 411 and can control the flow rate supplied from the working fluid pump 330 to the swing actuator 411.

In some examples, the quick coupler 100 may include a quick coupler cylinder 130 as shown in FIG. 1. While the uncoupling command (UC) input to the input unit 700 is maintained, the quick coupling valve 600 can operate the quick coupler cylinder 130 to allow the flow of the first working fluid from the working fluid pump 330 to the quick coupler cylinder 130 so that the working tool is uncoupled from the quick coupler 100.

In some examples, the working machine may include a driving unit 350 that drives a working fluid pump 330. The driving unit 350 is a power source that drives the pump and may include, for example, an engine, an electric motor, and the like. According to a preset relationship in which the second switching amount decreases as the rotational speed of the driving unit 350 increases, the size of the second switching amount can be configured to vary depending on the size of the rotational speed of the driving unit 350. Therefore, if the preset rotational speed of the driving unit is large, the flow control valve 430 can be switched to a small size of the second switching amount.

In some examples, the working machine may include an electronic control unit 540. According to a preset relationship in which the second current value decreases as the rotational speed of the driving unit 350 increases, the electronic control unit 540 can control the electronic proportional pressure reducing valve 531 so that the size of the second current value varies depending on the size of the rotational speed of the driving unit 350. Therefore, if the preset rotational speed of the driving unit is large, a small second current value can be provided to the electronic proportional pressure reducing valve 531. This will be explained in more detail below.

The operation signal of the input unit 700 can be transmitted to the electronic control unit 540. In FIG. 9, an example is shown in which the quick coupling valve 600 and the signal applying valve 533 are operated according to the operation signal of the input unit 700, but in some other examples, the quick coupling valve 600 and the signal applying valve 533 may be operated according to the control signal of the electronic control unit 540 that receives the operation signal of the input unit 700.

In order to enable the quick coupler 100 to be uncoupled simply by operating the driver's input unit 700, if the working fluid pump 330 and the quick coupling valve 600 are connected and the driver inputs an uncoupling request into the input unit 700, the pressure of the fluid supplied from the pilot pump 340 switches the flow control valve 430, and accordingly, the flow path which bypass the fluid from the working fluid pump 330 to the tank 200 through the inside of the main control valve 400 is blocked, and the fluid supplied from the working fluid pump 330 is supplied to the quick coupler cylinder 130 of the quick coupler 100 through the quick coupling valve 600, thereby moving the quick coupler cylinder 130 so that uncoupling can be performed simply by operating the input unit 700.

In this case, as shown in FIG. 3, high pressure P1 is supplied directly to the quick coupler cylinder 130. In this state, when the swing actuator 411 that uses the working fluid pump 330 together is operated, the high pressure P1 that has already been formed in the flow path between the working fluid pump 330 and the flow control valve 430 is immediately applied to the swing actuator 411, causing a shock and making fine operation impossible. To solve this problem, sudden operation can be reduced to some extent by lowering the rotational speed of the driving unit 350 to a low speed to minimize the flow rate and operating the swing actuator 411, but, even if the flow rate is reduced, the pressure is high, so the shock is not completely relieved, and it may take too long to uncouple the quick coupler 100, which may be an inconvenient problem.

To solve this problem, an electronic proportional pressure reducing valve 531 is installed in the signal line between the pilot pump 340 and the flow control valve 430, and the electronic control unit 540 adjusts the current value input to the electronic proportional pressure reducing valve 531 after a certain period of time T1 to lower the secondary pressure of the electronic proportional pressure reducing valve 531, thereby reducing the switching amount of the flow control valve 430. As a result, the fluid supplied from the working fluid pump 330 is not completely blocked by the flow control valve 430 of the main control valve 400, but some of the flow is bypassed to the tank 200 and some of the flow is delivered to the quick coupler 100, thereby it is configured to reduce the outlet pressure of the working fluid pump 330. The P2 pressure that drops after a certain period of time T1 is set to a pressure that prevents the quick coupler cylinder 130 from being pushed back into the coupling state by the elastic force of the elastic member (such as a spring) that applies force to couple if the P2 pressure is too low while the quick coupler 100 is in an uncoupling state.

Meanwhile, since, when the rotational speed of the driving unit 350 is low, the supply flow rate of the working fluid pump 330 is low, and when the rotational speed of the driving unit 350 is high, the supply flow rate of the working fluid pump 330 is high, if the P2 pressure is set based on the rotational speed of the driving unit 350 being low, the flow rate is high when the rotational speed of the driving unit 350 is high, and the P2 pressure is high, which causes a problem of sudden operation, and if the P2 pressure is set based on the rotational speed of the driving unit 350 being high, the P2 pressure is too low when the rotational speed of the driving unit 350 is low, and a problem may occur in which the quick coupler 100 is switched back to the coupling position due to the elastic force of the elastic member.

Table 1 shows the variation of P2 pressure according to the rotational speed of the driving unit 350.

TABLE 1
T1(s)	2.0
T2(s)	5.0
I1(mA)	1400

	RPM settings	I2(mA)	1	1000
			2	1000
			3	1000
			4	1000
			5	1000
			6	1000
			7	1000
			8	1000
			9	1000

P1(kgf/cm2)

280

	RPM settings	P2(kgf/cm2)	1	34
			2	49
			3	62
			4	75
			5	83
			6	93
			7	102
			8	112
			9	121

To further improve these problems, as shown in Table 2 below, the secondary pressure from the electronic proportional pressure reducing valve 531 is adjusted by adjusting the current value input to the electronic proportional pressure reducing valve 531 according to the rotational speed of the driving unit 350, and accordingly, the switching amount of the flow control valve 430 can be adjusted to adjust the opening area of the flow control valve 430. The opening area of the flow control valve 430 is formed to cope with the increase in flow rate due to the increase in RPM of the driving unit 350, so it is configured to minimize the change in P2 pressure according to the setting of the rotational speed of the driving unit 350. The amount of current value adjustment input to the electronic proportional pressure reducing valve 531 and the results according to this technology are shown in Table 2 below and FIG. 10.

TABLE 2
I1(mA)	1400

	RPM settings	I2(mA)	1	1000
			2	1000
			3	950
			4	950
			5	950
			6	900
			7	900
			8	850
			9	850

P1(kgf/cm2)

280

	RPM settings	P2(kgf/cm2)	1	50
			2	45
			3	52
			4	47
			5	53
			6	45
			7	50
			8	52
			9	55

FIG. 10 is a graph showing the results of adjusting the current value input to the electronic proportional pressure reducing valve 531 according to the rotational speed setting of the driving unit 350.

In FIG. 10, ‘a’ represents the second current value of Table 1 input to the electronic proportional pressure reducing valve 531, ‘b’ represents the adjusted second current value of Table 2 input to the electronic proportional pressure reducing valve 531, ‘c’ represents the P2 pressure of Table 1, and ‘d’ represents the P2 pressure of Table 2.

Meanwhile, even in the case where the secondary pressure from the electronic proportional pressure reducing valve 531 is adjusted as described above to maintain the pressure of P2 at a certain level, there are many different types of quick couplers 100 from each company, and most of these products have different elasticity of elastic members depending on the characteristics of each company. Some companies' products are set low, and some companies' products are set high. In this way, even when applying various products from each company, in order to prevent the aforementioned problems, such as when operating the swing actuator 411 after uncoupling of the quick coupler 100, the current value of the electronic proportional pressure reducing valve 531 can be adjusted to, for example, 90% or 110% of the initial setting value with an adjustment mode of the electronic control unit 540 from the value set when the equipment was first released, so that smooth operation is possible without problems even with different quick couplers 100 for each country/region and company. In some examples, it may be permissible to set the size of the second current value according to the size of the force by the elastic member.

In the above description, an example is described in which the working fluid pump 330 connected to the straight travel valve among the three working fluid pumps 310, 320, 330 illustrated in FIG. 9 is connected to the quick coupler 100, but it is also possible to similarly connect the quick coupler 100 to the working fluid pumps 310, 320 connected to other center bypass valves of the main control valve 400 and configure it so that pressure is supplied to the quick coupler 100 when the input unit 700 is switched on. In the above description, it has been described that, for example, swinging of the upper body of the excavator is necessary to change the working tool; however, in addition to or instead of this, for example, a lifting operation of the arm or boom of the excavator may be necessary. Accordingly, the present disclosure can also be applied to a structure in which a quick coupler 100 is connected to a working fluid pumps 310, 320 connected to an arm actuator control valve or a boom actuator control valve.

The terms used herein are for the purpose of describing certain aspects only and are not intended to limit the present disclosure. Unless the context explicitly indicates otherwise, plural forms may be included even if written in singular form. Additionally, the term “and/or” includes any and all combinations of one or more of the associated listed items. The term “comprising” specifies the presence of stated features, integers, steps, operations, elements and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.

Comparative terms such as “below,” “above,” “further up,” “further down,” “horizontal,” or “vertical” may be used herein to describe the relationship of any element depicted in the drawings to another element. These terms and the foregoing may include other orientations of the device as well as the orientation depicted in the drawings. When an element is referred to be connected or coupled to another element, this may mean not only a direct connection, but also other intervening elements. On the other hand, when an element is referred to be directly connected or coupled to another element, it implies that there are no intervening elements.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present disclosure belongs. The terms used herein should be interpreted to have meanings consistent with their meanings in the context of this specification and the related art, and will not be interpreted in an idealized or overly formal sense, unless expressly defined herein.

The present disclosure is not limited to the aspects described above and illustrated in the drawings, but rather, those skilled in the art should appreciate that various changes and modifications may be made within the scope of the present disclosure and the appended claims. While many aspects have been disclosed in the drawings and specification for purposes of illustration and not limitation, the scope of the present inventive concept is set forth in the claims that follow.